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Author Topic:   Pressure Washing
cvyarb posted 09-04-2014 08:33 PM ET (US)   Profile for cvyarb  
Hi all,

Anyone have any idea what the max psi one can safely pressure wash a Whaler would be? I have heard different estimates and I need to get mold off, but also don't want to destroy the fiberglass (this is inside the hull and on the deck).

Many thanks!

WhatKnot posted 09-04-2014 08:52 PM ET (US)     Profile for WhatKnot    
I have used various electric power washers over the years and have never had a problem. Gas powered may be another story.
cvyarb posted 09-04-2014 08:59 PM ET (US)     Profile for cvyarb    
Thanks for responding. That's sort of what I was wondering.

I need to get the mold off the cockpit deck, but I also don't want to damage anything. I've used a pressure washer extensively, but I'm not sure whether an electric one will effectively remove the mold.

Did you pressure wash mold off? I have no idea how hard it is to get rid of...

contender posted 09-04-2014 09:53 PM ET (US)     Profile for contender  Send Email to contender     
Does not matter if you have a gas or electric power washer the problem is how close you get to the boat with the tip and what tip you use, I would spray the boat down with clorox/bleach and let it sit a while, then do the pressure wash. I have a Gas Honda 4000 psi and I use it all the time
cvyarb posted 09-04-2014 09:59 PM ET (US)     Profile for cvyarb    
Ok, thank you. I will mind how close I am, and I appreciate the feedback.
PeteB88 posted 09-04-2014 10:51 PM ET (US)     Profile for PeteB88  Send Email to PeteB88     
Use Simple Green, Amazing Roll Off or Krud Cutter first, let it soak a while, then scrub with proper soft/medium deck brush on a pole rinse it out - see what comes off then go to power washer about medium pressure, wide pattern jet and you got it.
cvyarb posted 09-04-2014 11:14 PM ET (US)     Profile for cvyarb    
Ok, good advice. Thank you.

The only problem is that I've been told by the surveyor that it is black mold and so it's dangerous. Hence I figured I would wear a respirator and hit it with a pressure washer to knock as much off as I could, and then try the scrubbing part after most of the mold material was gone. Hopefully the result is then there was less crud for me to potentially breath in and that could get me sick.

Also, the surveyor said that I could try to put a bleach mixture in a plant sprayer (weed killer sprayer) and that would be the best way to get any mold from the bilge. I've heard that a water/bleach mixture won't kill mold, that it comes back after a while. Anyone have any thoughts on that?

I'm in slightly over my head but I will get this done. Thanks for everyone's help.

RevengeFamily posted 09-05-2014 06:38 AM ET (US)     Profile for RevengeFamily  Send Email to RevengeFamily     
If you were in an enclosed space handling items that were covered in mold I would worry and definitely wear a respirator. Since you will be outside and you will be wetting the mold down with a solution of bleach I would not get crazy about being exposed to mold spores in the air.

Every spring, I power wash my boats. The solution I use is made up of approximately a half-cup of bleach added to two gallons of water with two or thee drops of DAWN dish detergent to break the surface tension of the water and bleach solution. If you don't add the detergent, the water and bleach doesn't seem to soak into and loosen the dirt and mold.

I have been using this solution for years and have never had a problem. I have also been using my Honda gas powered pressure washer which is rated at 3000-PSI with no problems.

The mold "comes back" because there will be all sorts of yummy things on the deck for it to grow on after a fun filled summer of boating. The bleach you spray on your boat will be washed off and therefor will not give any further "protection" against new mold that will find your boat. There are mold spores in the air you breathe every day.

Relax and enjoy your new boat.

jimh posted 09-05-2014 09:03 AM ET (US)     Profile for jimh  Send Email to jimh     
I have noticed this general tendency: if a man purchases a power tool, the man will find as many places as possible to use the power tool. The corollary: if a man owns a high-pressure power-washer, he will use it to wash things he also owns.

Whether or not using the spray from a very high pressure power-washer is the best method of cleaning the gel coat surfaces of Boston Whaler boats is subject to some debate. Here is my personal experience: I don't own a power-washer, and, accordingly, I don't use one to wash my Boston Whaler boat. I wash it with a rather mild solution of 3M BOAT SOAP and water. I try to keep the boat gel coat surfaces waxed so that surface dirt will be unable to get adhesion to the gel coat. This allows most surface dirt to be removed with a very mild soap and water solution and a wipe with a soft sponge or brush. I try to keep up with the dirt, washing it away frequently, and not allowing it to become baked on for months in the sun.

Jefecinco posted 09-05-2014 09:34 AM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
My opinion and practice is the same as Contender's. I have owned and used a Honda powered 3800 PSI power washer for several years. I bought and used the washer for a few years to clean up the dirty concrete drive and sidewalks and to power wash my home. Mildew is the primary exterior paint destroyer in the deep south and I power wash our home annually.

Before taking a pressure washer to the Whaler I had a lot of hours of using it. That has been useful when power washing the Whaler. I recommend the least aggressive tip and the use of some extra caution around caulking and decals. Wear leather shoes as power washing your toes is contraindicated. Practice a little on your driveway to get the feel of the washer you'll be using.


Hoosier posted 09-05-2014 10:13 AM ET (US)     Profile for Hoosier  Send Email to Hoosier     
My Whaler owner's manual says to us ammonia to kill mold, not bleach. I've used it on the deck on my house and the mold does not come back.
cvyarb posted 09-05-2014 11:33 AM ET (US)     Profile for cvyarb    
Thank you everyone for chiming in.

These are all great suggestions, and now I am looking forward to tackling this beast of a project. I will be doing this in the next week or two and will post some before/after shots once I figure out how to post pics.

hauptjm posted 09-05-2014 02:24 PM ET (US)     Profile for hauptjm    
... if a man purchases a power tool, the man will find as many places as possible to use the power tool.

Reminds me of an old saying my Grandfather used to say, "Give a Man a hammer and everything looks like a nail."

fno posted 09-05-2014 06:13 PM ET (US)     Profile for fno  Send Email to fno     
A word of caution!! Keep the pressure washer away from your vinyl if it has any real pressure. It will eat the vinyl faster than you can blink.
jimh posted 09-05-2014 07:39 PM ET (US)     Profile for jimh  Send Email to jimh     
Very wise Grandfather.
Jefecinco posted 09-05-2014 07:42 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
True. I would not pressure wash vinyl. I remove all my vinyl before washing the boat and installing the cover at the end of the boating day. It then gets a little 303 to keep it nice and remove any mess. I install it only before using the boat. My vinyl has no mold and has never had any.


cvyarb posted 09-05-2014 09:51 PM ET (US)     Profile for cvyarb    
Ok, thank you guys. Definitely not going to spray the vinyl, and will use the suggestions to do it all the right way.

I really appreciate the input.

deepwater posted 09-06-2014 12:02 AM ET (US)     Profile for deepwater  Send Email to deepwater     
Did the surveyor give you any good idea how to kill the black mold? If bleach wont kill it is there anything we can buy over-the counter? Or do we need a yearly contract for repeated treatments?
Ridge Runner posted 09-06-2014 01:15 PM ET (US)     Profile for Ridge Runner  Send Email to Ridge Runner     
Both bleach and ammonia have been mentioned here... what ever you do don't mix them. It will make Chlorine Gas (among other ugly things).

Household bleach has a chemical formula of NaOCl - that is, one atom each of sodium, oxygen, and chlorine. Its chemical name is sodium hypochlorite. Ammonia has a chemical formula of NH3, that is, one atom of nitrogen and three atoms of hydrogen. When these two compounds are combined, the following reaction takes place:

2NaOCl + 2NH3 --> 2NaONH3 + Cl2.

That Cl2 on the right hand side means one part chlorine gas, made up of diatomic (two-atom) molecules. It also means that the chlorine gas has been liberated from the bleach, and is quite capable of causing of killing you when inhaled.

Nitrogen Trichloride (very toxic)

Another potential reaction, which occurs when a greater amount of bleach is added than ammonia, is this:

3NaOCl + NH3 --> 3NaOH + NCl3

That's sodium hydroxide and nitrogen trichloride. Nitrogen trichloride is a very toxic chemical it is also a very volatile explosive.

Hydrazine (rocket fuel) Another reaction can occur if you have more ammonia than bleach. It is a three-part process. The first reaction produces sodium hydroxide and chloramine.

NH3 + NaOCl --> NaOH +NH2Cl These products react with more ammonia.

NH3 + NH2Cl + NaOH -->N2H4 + NaCl + H2O.

N2H4 is hydrazine, a very unstable compound.

Then a final reaction between hydrazine and dichloramine occurs.

NH2Cl + N2H4 --> 2NH4Cl + N2.

This reaction produces so much heat that it usually causes an explosion.

Jefecinco posted 09-06-2014 07:20 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
I seem to create chlorine gas every time my wife puts bleach in my commode. It only takes me a couple of seconds to realize what's happened.
cvyarb posted 09-06-2014 08:07 PM ET (US)     Profile for cvyarb    
Deepwater--the surveyor agreed with my research that, for black mold, pressure washing is the best way to get rid of it permanently. For the areas that can't be reached that way, he believes bleach is best. That said, I will be contacting Servicemaster Cleaning to ask them some questions. He indicated that he's used them for boats that have had mold/submersion issues.

I can circle back late down the line when I get more info. I think most people are thinking this is just normal mold issues, but unfortunately it's much worse than that. Regardless, I will prevail.


RevengeFamily posted 09-07-2014 04:56 AM ET (US)     Profile for RevengeFamily  Send Email to RevengeFamily     
If those photos in the above mentioned link is your project Whaler, get the shrink wrap off the vessel first. You won't want to work with bleach underneath the plastic. Ultra-violet light is very detrimental to black mold. Best of luck and keep us posted.--Norm
cvyarb posted 09-07-2014 11:04 AM ET (US)     Profile for cvyarb    
It is and I will Norm, thanks for the well wishes.
EJO posted 09-12-2014 03:48 PM ET (US)     Profile for EJO  Send Email to EJO     
Apparently the surveyor knows a lot about mold remediation?
You got all good answers and advice, but if you really want to get rid off the mold you must have the mold spores tested.
The testing lab then can determine of a "regular" bleach or "regular" ammonia with water mixture will kill it or if something else is needed.
Some spores will not be killed by either no matter what the pressure washer pressure is.
Powergroove803 posted 09-22-2014 03:43 PM ET (US)     Profile for Powergroove803  Send Email to Powergroove803     
Ridge Runner, very good stuff, kinda "Breaking Bad" stuff we all need to know, even the wives.
I use the pressure washer at the car wash and have had no ill effects on my paint or far.
It does clean it effectively and I do hold it much further away when Im spraying the vinyl.

I had an old White GMC truck once that I primarily went offroad with, lots of dirt and mud. I went to the carwash and didnt notice that the dial was turned to "tire cleaner". My white truck was never cleaner than after I sprayed her down with that stuff, whatever it was. Of course it left no wax either!

Jefecinco posted 09-22-2014 04:09 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
Car wash pressure nozzles are nothing compared to the output of a pressure washer.
Binkster posted 09-22-2014 09:48 PM ET (US)     Profile for Binkster  Send Email to Binkster     
No way you can ruin gelcoat or Awlgrip by spraying with a pressure washer, unless your using the pencil tip, maybe. Gelcoated offshore race boats run over 140mph, and they don't leave the gelcoat out on the ocean.


pcrussell50 posted 09-24-2014 07:59 PM ET (US)     Profile for pcrussell50  Send Email to pcrussell50     
I don't know the severity of the mold you're talking about, but I've gotten mold off of medium-oxidized hulls (in other words, oxidized surface good for mold to grip on to), with soapy water and a scrub brush. And it came off pretty easily too. Not too much elbow grease.


americanwashing posted 07-12-2015 10:51 PM ET (US)     Profile for americanwashing    
wow! thanks for the very useful infos!
porthole2 posted 07-14-2015 02:06 AM ET (US)     Profile for porthole2  Send Email to porthole2     
For mold and mildew I use Krud Kutter. For deep seated mildew particurly in areas that are covered (under the console - decks etc) I use Tilex mildew root remover.

Do what you want, but I would be careful using pressure washers on older boats that may have not been well cared for. The gunnels seem especially prone to getting loose brittle areas. The curved surfaces on the gunnels tend to have voids between the FRP and the gelcoat.

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